In the case that a solid image that has been prepared on the basis of the three-dimensional coordinate system is to be displayed on a two-dimensional image display device such as an analog display, the solid image is projected onto a display screen of the image display device from one viewpoint as a reference.
The solid image is displayed on the display screen in the form of polygons or a wire frame. In the case that the solid image is displayed in the form of polygons, the solid image is formed by a plurality of polygons such as triangles or the like. In order to project the solid image onto the display screen, coordinates of vertexes of each polygon of the three-dimensional coordinate system are transformed to those of a polygonal two-dimensional plane. After transformed, each polygonal plane is painted out by being subjected to a shading process, a texture mapping process, luminance processing and the like. A solid image which has been projected onto the display screen from a certain viewpoint may be correctly generated by writing pixels over one another in order in which a pixel which is positioned distant from the viewpoint is written earlier than others.
A lenticular display is available as an image display device which is configured to display a solid image which has been projected from a plurality of viewpoints, in contrast to the analog display that displays the solid image which has been projected from one viewpoint. The lenticular display is configured to display a solid image in such a manner that its form changes as the viewpoint is shifted by generating two-dimensional images obtained by projecting one solid image from a plurality of viewpoints and compositing the plurality of generated two-dimensional images with one another.
In the case that a process of projecting an image onto a display screen is executed by setting a plurality of viewpoints which are arranged in a line, the more the number of viewpoints is increased, the more the throughput is increased. A technique for generating two-dimensional images which have been projected onto a display screen from a plurality of viewpoints by interpolation arithmetic processing executed using two-dimensional images which have been projected onto the display screen from two viewpoints is proposed as disclosed, for example, in “A 36 fps SXGA 3D Display Processor with a Programmable 3D Graphics Rendering Engine”, Seok-Hoon Kim et al, IEEE International Solid-State Circuits Conference, 2007, pp. 276-277, 2007.